Suicide rates are expected to rise when an estimated 400 mental health carers take retirement this month, it has been revealed.

Psychiatric Nurses Association (PNA) claimed vital services would be cut for Ireland's most vulnerable, as staffing levels plummeted around the country.

Des Kavanagh, general secretary, said up to 10% of whole time posts would retire within weeks, on top of an estimated 1,200 staff who quit over the last two years.

"In this current environment where we are cutting admission beds, cutting staff in the community and, in places, cutting doctors, we are increasing the risk to the mentally vulnerable and the potential for suicide," he warned.

Official figures show 486 people died by suicide in Ireland in 2010. "In the old days with big mental hospitals at least there were beds, in the future, families will be trying to cope with mentally ill family members," he added.

Mr Kavanagh said psychiatric staff were demoralised, worn out and already struggling to meet demand. He criticised PR campaigns around mental health while there was no investment in preventative services.

And he revealed there was little follow-up of the estimated 12,000 people who were admitted to emergency departments each year from self-harm. "I think it's totally irresponsible of our society to be depending on the goodwill of wonderful people who established so many groups out there to work with the bereaved and work with those who are suicidal," he added.

The PNA survey of its own branches found that up to 400 frontline nurses were to retire under the Government's early retirement scheme.

Mr Kavanagh, who described the handling of the scheme in the health service as a shambles, said he was not yet aware of any plans in place around the country to deal with the pending staff shortage.

"If we don't engage, there is a very real danger we will end up in pandemonium, that it will be whole scale closure of services, last minute panic reactions to not having enough staff, and people going without services," he said. "It is a frightening prospect."